Value of ultrasonography in the diagnosis of carpal tunnel syndrome—a new ultrasonographic index in carpal tunnel syndrome diagnosis

Abstract

We analyze the effectiveness of ultrasonography in diagnosing carpal tunnel syndrome (CTS) and propose the use of sonographic index of median nerve (MN) in carpal tunnel (SIMNCT) in a diagnostic algorithm and in establishing a scale of severity. We studied a group of 344 patients with CTS symptoms, examining them by ultrasound. We measured in all patients, on the affected hand: the size of the cross-sectional area of the MN at carpal tunnel (CT) inlet and outlet, nerve morphology at passage through CT, the vertical thickness of the MN entering into the CT – G1, the lowest vertical thickness into the CT or leaving the CT – G2, the thickness of the MN in the transversal plane as entering in the CT – L. Normal values were considered the similar measurements taken on the healthy hand and we established as normal SIMNCT = 16%. We proposed the formula SIMNCT = 100% (1-G2/G1) in order to calculate the index. Statistics show a significant sensitivity of SIMNCT ( P < .0001) compared with cross-sectional area (CSA) and flattening ratio in the diagnosis of CTS. Analyzing the SIMNCT developed by us, we demonstrated a sensitivity of 94.81% and a specificity of 99.66% in CTS diagnosis. Thereby, we propose a CTS severity classification: normal = 16%, mild = 16–19%, moderate = 19% to 28%, severe = 28% to 50%, very severe > 50%. Ultrasonography is an effective method of studying the morphology of the tunnel and compressed nerve at various CTS stages and determining the cause of compression. The SIMNCT is a valuable and practical indicator and it can be used in the CTS diagnosis.

Diagnostic utility of anteroposterior measurements of the median nerve on sagittal ultrasonographic images and their correlation with clinical findings in carpal tunnel syndrome

“…29 Pert ¸ea et al recently reported a method of diagnosing CTS using almost the same formula as ours based on measurements obtained from a sagittal ultrasonographic image of the median nerve. 13 They reported that a stenosis rate of 16% or greater had a sensitivity of 94.81% and specificity of The present study had some limitations. First, the sample size was small.…”

“…11 Several studies have shown that morphological changes of the median nerve (stenosis of the median nerve in the distal carpal tunnel and swelling of the median nerve in the proximal carpal tunnel) were observed on sagittal ultrasonographic examination of patients with CTS. [7][8][9][11][12][13] In a study similar to ours, the ideal cut-off values of the MND for the diagnosis of CTS on sagittal ultrasonography were reported to be 2.235 mm for the proximal carpal tunnel and 1.755 mm for the distal carpal tunnel. 7 Furthermore, another study reported that these morphological changes of the median nerve on sagittal images were observed in 90% of patients with CTS.…”

“…Diagnostic criteria for objective examination methods such as ultrasonographic examination and electrodiagnostic (EDX) testing have been proposed. [4][5][6][7][8][9][10][11][12][13] Some scholars believe that CTS should be diagnosed based on clinical symptoms and does not require objective examinations, such as EDX testing. 14 However, some conditions may cause symptoms similar to CTS, including cervical radiculopathy, peripheral neuropathy, and tendinitis and tenosynovitis around the hand.…”

“…In CTS, ultrasonography has been reported to show stenosis of the median nerve compressed by the transverse carpal ligament at the distal carpal tunnel and enlargement of the median nerve at the carpal tunnel entrance, [4][5][6] and several studies have reported the observation of these changes on sagittal ultrasonographic images. [7][8][9][11][12][13] Diagnostic criteria for CTS determined from the patient's manifestations and physical examination findings have also been reported.…”

The Impact of Reference Standard on Diagnostic Testing Characteristics for Carpal Tunnel Syndrome: A Systematic Review

“…The diagnostic tests evaluated and their weighted mean sensitivity and specificity are outlined in Tables 2 and 3. 16-128 Although studies utilizing “clinical diagnosis” as a reference standard were treated as a unified subset, many studies 16-128 were found to utilize different definitions of clinical diagnosis. An outline of the utilized definitions for “clinical diagnosis” is presented in Supplemental Digital Content 1.…”